Printing cylinders, particularly for use in photogravure printing, but also suitable for use in some copy apparatus, have previously been made by mechanically working steel cylinders of relatively long axial length, polishing the cylinders and balancing them, since they must be operated at high speed. These cylinders usually are of thick wall construction since, particularly at high printing speed, they are subject to substantial mechanical stress.
The steel cylinder, forming a carrier, has a copper layer of about 1 mm thickness applied to its circumference, typically by electrolytic deposition. This layer must be smooth at the outer circumference and dense. Thus, during deposition, which takes about 15 hours, it is continuously compacted by a jewel roller, for example of agate, and rolling with the steel cylinder on which the copper layer is being deposited. This copper layer, then, has a layer of silver applied thereover; over the silver layer, a further copper layer is electrolytically deposited. The final or further copper layer then is used as the printing surface. After the customary photolithographic processes, the depressions within the outer copper layer are etched in by a chemical etch. The depth of the depressions or engravings are in the order of about between 0.02 to 0.03 mm.
The printing roller, that is, the composite of steel body, copper layer, silver separating layer, and final copper printing layer, is then used in printing, for example magazines and the like. After the printing run is completed, the outer coating is removed from the printing roller by mechanical means, particularly by stripping off the outer layer using tongs, gripping instruments, and the like. A new silver layer is then applied, a new copper layer deposited over the silver layer, and the cylinder can be re-used for a renewed photographic exposure, etching, and ready for printing with a new subject matter.
The system above described, which is well known and has been practised over many decades, has one disadvantage: It is difficult to remove the outer copper jacket. During this removal step, damage to the roller body, forming the base thereof, frequently occurs. This, then, requires reworking of the printing roller, usually by the manufacturer, thus disassembly of the roller from a printing machine, re-assembly, shipping, and the like. Since the rollers are heavy, difficult to handle, and awkward due to their size and shape, reworking is expensive.